Wood staining



Patented May 7, 1935 STATES PATENT OFFICE Charles J. Pedersen,

. ware No Drawing.

7 Claims.

This invention relates to the staining of fibrous materials and moreparticularly to the production of stains by the catalytic oxidation oforganic compounds on said fibrous materials.

Heretofore wood has been stained by one or two general methods. By thefirst method the wood to be stained was treated with dye solutions toallow it to absorb the dyes. The great objection to the use of thismethod has been the poor penetration attained.

By the other method the staining has been accomplished by the oxidationof aromatic organic compounds on the wood fibres, the oxidation beingbrought about by the use of chemical oxidizing agents in the presence 01mineral acids. The disadvantages of this last named method were theresultant tendering oi the wood and the effiorescence of the resultantcompounds'on the surface of the wood.

This invention has for an object the production of a stain with greatpenetrating power and insolubility. A further object is the staining offibrous materials without use of chemical oxidizing agents and mineralacids. Still further objects are the production of a material adaptedfor rapid staining of wood, the production of a very fast stain, a verydeep stain, a stain which is unaccompanied by tendering of the fiber, astain which is unaccompanied by emorescence and in general anadvancement of the art. Other objects will appear hereinafter.

These objects are accomplished by this invention by which certainsubstituted amines or diamines are catalytically oxidized on or in thematerial to be stained. The invention will be readily understood from aconsideration of the following examples in which the parts are given byweight.

Example I There wasdissolved in '15 ml. of the monoethyl-ether ofethylene glycol 1 gm. of cupric chloride, and to the solution was added25 ml. of toluene. Fifteen (15) gms. of m-toluylene diamine wasdissolved in the resultant mixture. A piece of wood was heated to thetemperature of 150 F. and then dipped into the solution while stillwarm. The wood was allowed to soak for 30 minutes after which it waswithdrawn wiped, dried and finished. In the examples carried out it hasbeen found that cooling the. wood in the solution greatly aids thepenetration of the stain.

Example II In this example all figures are based upon the originalweight of the alcohol. To a 1% solution Carneys Point, N. J., assignorsto E. I. du Pont Wilmington, DeL, a corporation of Delade Nemours & Com-Application December 23, 1930, Serial No. 504,426

(Cl. 91-68) A Example III A sample of wood was first soaked in a 15%solution of m-toluylene di-amine in alcohol. Thereafter the surfaceliquid was wiped off and the wood dipped into a 1% solution of cupricchloride in alcohol. Oxidation started imme diately at the surface andalthoughthe color developed below the surface of the wood somewhatslowly due to therate of diffusion of the air to the interior of thewood, the visible portions of the wood were stained even when scraped tothe depth of the penetration of the m-toluvlene diamine.

Other organic compounds than the m-toluylene di-amine of the aboveexamples may be used satisfactorily. In general other aromaticdi-amines, for example, m-phenylene-di-amine, p-phenylene-di-amine, andm-naphthylene-di-amine, are suitable. There may also be used aromaticamines which are characterized by containing activating or positivegroups, for example, the hydroxyl, the alkoxy and amino groups in thering and containing no n'e'gative groups or substituents, such as, thecarboxyl, the sulphonic and nitrile groups in the ring. As examples ofsuitable compounds of this class there may be mentioned p-amino-phenoland p-amino-anisole. As examples of aromatic amines which areunsatisfactory because of negative groups in the ring may be mentionedsulfanillc acid, anthranilic acid and -chloro-m-toluidine-p-sulphonlcacid.

The term negative substituent as used in this application has its usualmeaning, namely, that it tends to increase the negative character ordecrease the positive character of the molecule of which it is a part.The unsubstituted aromatic amines, for example, aniline and thetoluidines have not been found oxidizable under the conditionsdescribed.

It is sometimes desirable to add a wetting agent to the stainingcomposition in order to obtain better penetration as for examplesulfonated castor 011, one of the alkylated naphthalene sulfonic acidssold under the trade name of Nekal or tri- 'ly in order to meetparticular conditions.

ethanolamine oleate or other ethanolamine soap. Catalysts other than thecupric chloride of the examples are suitable. In general any solublecupric salt, for example, cupric acetate may be used. The soluble saltsof vanadium are suitable.

The invention is not limited to those solvents mentioned in the aboveexamples, for example, benzene and acetone, give satisfactory results.In general any organic solvent which may be classified as miscible orimmiscible with water is suitable. Water itself may be used in caseswhere it is not harmful to the success of the process. The disadvantagesof using water are that it causes swelling of the wood and thereforerequires considerable time for the wood to regain its normal dimensionsin order that it may be further processed. Another objection to the useof water is present in the case where the wood to be stained containsglued joints. The water loosens the joints.

' Inthe case where the material to be stained is not swelled by waterits use as a solvent is quite satisfactory especially with the moresoluble compounds such as m-phenylene di-amine and the like.

-' All of the solvents covered by the above description may be generallydivided into two' classes known as polar, that is, one in whichionization takes place and non-polar, that is, one in which ionizationis not appreciable, solvents.v Where polar solvents are used thebasicity of the amine or di-amine substance may cause precipitation ofthe catalyst and it is therefore necessary to add "to the solution amaterial which will causeretenthe invention is broadly applicable tofibrous ma 'terials. Mention may be made of asbestos, wool, paper, paperpulp and fur. v

The method of application may be varied wide- For instance in theprocess of Example HI the order of application of the materials may bereversed. In other instances better and more rapid penetration may besecured by applying the stain producing compound under pressure. Thepenetration can be varied to the desired degree by the time of soaking.The method of drying may be modified as required by specific situations.same generality applies to the concentration of the solutions used inthe process and the temperature for the drying.

This invention has numerous advantages as will be obvious from aconsideration of the specification. Because organic solvents are usedwood articles comprising joints held together by water soluble glue maybe stained satisfactorily. Furthermore, use of solvents of thischaracter because of their high volatility results in quick drying ofthe material (30 minutes penetration of these compositions beingequivalent to several hours penetration of the compositions heretoforeknown) and consequently permits rapid processing. *Rapid processing is,further aided by the fact that these solvents do not swell the woodbeing treated (as does water) and therefore the time required to allowan article to regain its normal size is eliminated. 'Because no Themineral acids are used in this invention tendering of the fibers of thematerials stained is avoided. Because of the absence of chemicaloxidizing agents in the process efilorescence, on the stained article isnot present. Another great advantage of the invention is that the stainsproduced are extremely fast and are not extracted by any ordinarymethod. Still another advantage is present in the fact that the grain ofthe wood stained according to this invention is not obscured.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that we do not limit ourselves to the specific embodimentsthereof except as defined in the appended claims.

We claim:

1. The process of staining Wood which comprises treating the wood with acomposition of matter comprising an organic solvent selected from thegroup consisting of alcohol, the monoethyl ether of ethylene glycol,benzene, acetone and toluene, a member selected from the groupconsisting of m-toluylene-diamine, m-phenylenediamine,p-phenylene-diamine, m-naphthylenediamine, p-amino-phenol, andp-amino-anisole, and cupric chloride, and thereafter exposing thetreated material to the action of air.

2. The process of staining wood which comprises treating the wood with asolution of cupric chloride in alcohol and aqua ammonia to which hasbeen added m-toluylene-diamine, and thereafter exposing the treatedmaterial to the action 'of air.

3. The process of staining wood which comprises treating the wood with asolution of mtoluylene-diamine in alcohol, subsequently treating thewood with a. solution of cupric chloride in alcohol, and thereafterexposing the wood to the action of air. v

4. A composition of matter comprising an organic solvent selected fromthe group consisting of alcohol, the mono-ethyl-ether of ethyleneglycol, benzene, acetone and toluene, a member selected from the groupsconsisting of m-toluylenediamine; m-phenylene-diamine,p-phenylenedlamine, m-naphthylene-diamine, p-amine-phenol, andp-amino-anisole, and cupric chloride, the ingredients being inproportions which, on exposure to air, impart a stain to woodimpregnated therewith.

5. A-composition of matter'comprising a solution of cupric chloride inalcohol and aqua ammonia to which has been added m-toluylene-di- 'anaromatic mono-amine having a positive group substituted thereon and anaromatic diamine having a positive group substituted thereon in asolvent inert to the fibrous material, in another operation impregnatingthe fibrous material with an oxidation catalyst in a solvent inert tothe fibrous material, and exposing the treated material to the action ofa gas containing free oxygen.

CHARLES J. PEDERSEN.

